Evaluation of Carabid Beetle Diversity in Different Bioenergy Cropping Systems

Benjamin Mast,Simone Graeff Hönninger,Wilhelm Claupein

doi:10.5539/sar.v1n2p127

Abstract

Changes in agricultural land use as a consequence of an increased demand of energy crops have resulted in an increase of maize cropped area in many regions of Germany. The focus on maize as main biogas substrate, has led in some cases to negative ecological and environmental impacts, such as a loss of agro biodiversity reflected in a loss of field flora and fauna biodiversity. The present paper deals with the evaluation of the fauna in different bioenergy cropping systems on two sites in South-West Germany, with a special focus on the species richness of carabid beetle (Coleoptera: Carabidae) assemblages as an indicator for the general status of diversity. A maize field, an agroforestry system with maize and different tree species as well as different alternative biogas crops (amaranth, sunflower) was investigated for their carabid beetle activity, density, and species richness using pitfall traps. Moreover, for an adequate evaluation of the carabid assemblages different common diversity indices (Shannon-Wiener diversity (H’), Simpson diversity (D) and Evenness (J’)) were used. In the case of the maize field on both field edges 8 and 6 carabid beetle species, respectively were trapped, while in the field centre 2 carabid beetle species were trapped. The agroforestry system indicated slightly higher crabid beetle species richness close to the tree strips. The investigation of alternative biogas crops showed no significant differences in carabid beetle diversity. Overall, the results of the different studies showed, that biodiversity of bioenergy cropping systems could be enhanced by the creation of refuge areas for carabid beetles or other animals. Refuges could be either field margins with grass and hedgerows or strips of more extensively used perennial energy crops across the field.

Highlights

Political targets on European and German level (Commission of the European Communities, 2005; BMU & BMELV, 2010) considering the expansion of energy from biomass have resulted in a shift of agricultural area formerly used for food production being used for energy production to satisfy the growing demand for energy crops
The highest number of individuals was collected from the carabid beetle species Pterostichus melanarius with 114 individuals and a relative abundance of 73.5 % of the total number of carabid beetles found at this experimental site
The results of the different studies showed, that carabid diversity of cropping systems could be enhanced by the creation of refuge areas, which could be field margins with grass or hedgerows

Summary

Introduction

Political targets on European and German level (Commission of the European Communities, 2005; BMU & BMELV, 2010) considering the expansion of energy from biomass have resulted in a shift of agricultural area formerly used for food production being used for energy production to satisfy the growing demand for energy crops. Maize is currently the main substrate for biogas production in Germany and in regions where a large number of biogas plants exists; a high maize density mainly cropped as maize monocultures often predominates. The general agricultural intensification led to a decline of biodiversity of agricultural landscapes caused by simplification of cropping systems, which resulted in reduced crop diversity and loss of non-crop habitats such as grassland and field boundaries (Stoate et al, 2001). These effects intensify with an expanding bioenergy production along with a strong focus on only a few important crops

Methods

Results

Conclusion